The present study explored psychological predictors of response to a series of three 25 second inhalations of 20% carbon dioxide-enriched air in 60 nonclinical participants. Multiple regression analyses indicated that only anxiety sensitivity physical concerns predicted self-reported fear, whereas both physical anxiety sensitivity concerns and behavioural inhibition sensitivity independently predicted affective ratings of emotional arousal. In contrast, the psychological concerns anxiety sensitivity dimension predicted ratings of emotional displeasure (valence), and both psychological anxiety sensitivity concerns and behavioural inhibition sensitivity independently predicted emotional dyscontrol. No variables significantly predicted heart rate. These data are in accord with current models of emotional reactivity that highlight the role of cognitive variables in the production of anxious and fearful responding to somatic perturbation, and help further clarify the particular predictors of anxiety-related responding to biological challenge.